Problems with the 2nd Droid Razr Maxx HD

I have gone through one maxx hd already. Before that I went through 3 different LG Spectrum 2's before I got the Razr Maxx hd. Here is the issue. Before on the LG's when I used the google navigation the phone would shut itself off and not repower back up. I went through 3 different phones from LG of the same phone. Finally get the Razr Maxx and it did the same thing. I was using navigation and it just shut itself off. Verizon told me to NOT use my old SD Card because it could have been a problem with google account or old apps on the sd card. I just got this new replacement wednesday and its sunday. I get up and its working fine. Hour or so goes by and it had shut itself off AGAIN!!!! I looked on the forum here for someone with the similar problem and all I could find was how to reset it holding the power and volume buttons. That worked but I still want to find out why my phone is shutting off like this. I don't have any sketchy apps. I use my personal banking app, capital one, nhl gamecenter and that is pretty much all i've downloaded. What the hell is happening to my phone? I made a new google account by the suggestion of the team at verizon. Any help would rock!